This PCB design is intended as a production-ready (mostly) SMT design. Unlike current SlimeVR designs by the community and the production batch that use the ESP8266, this board uses the very new ESP32-C3 chip, which is better in almost all respects than its predecessors.
The IMU is still a breakout board to better allow the community to experiment with different IMU options.
This board was designed to work with the following IMU breakouts, via solder jumpers that can reconfigure the board.
- BNO08X (Aliexpress GY-BNO08X and Adafruit BNO08X)
- MPU-6050 (Aliexpress GY-521)
- MPU-9250/6500 (Aliexpress GY-9250 and MPU-92/65)
- ICM20948 3.3v (Aliexpress GY-912 and Pimoroni PIM448)
As always, check to make sure your particular breakout board has the pins in the right spots for this PCB! Not all breakouts of the same IMU have the same pins!
First and foremost, the ESP32-C3 uses RISC-V as its instruction set, rather than XTensa. XTensa is not supported by LLVM (yet), or by the Rust programming language, without using a fork of the compiler. I wanted to use this design in future IOT projects as well, so targeting a more mainstream instruction set with better compiler support seems useful. It will also help me more easily use Rust with this device!
Secondly, the ESP32-C3 is similar in features to the ESP32 series of chips, but like the ESP8266, it is very cheap, making it a great choice. A few of the features it has over the ESP8266:
- Bluetooth LE v5.0 (even ESP32 only has v4.2)
- Stronger WiFi signal at a lower power usage than the ESP8266
- More RAM (400KiB vs 160)
- Built-in USB-serial and USB-JTAG support eliminates need for USB-UART chip
- JTAG debugging
- Sleep modes consume significantly less power
- New peripherals like security modules
- GPIO is more fully featured, and has more pins
For more info, this was a good article.
A description of the changes in each revision can be found here.
The original v0.1.0 design was based on the schematics of the esp-rs Rust board. Thanks to the esp-rs community for being so awesome! Also, thanks to the SlimeVR developers and especially @Eirenliel for making SlimeVR awesome and open source :)